Hardware Required

Circuit

Schematic

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Code

In the code below, a variable called analogValue is used to store the data collected from a potentiometer connected to the board on analogPin 0. This data is then compared to a threshold value. If the analog value is found to be above the set threshold the built-in LED connected to digital pin 13 is turned on. If analogValue is found to be < (less than) threshold, the LED remains off.

/*
Conditionals - If statement

This example demonstrates the use of if() statements.
It reads the state of a potentiometer (an analog input) and turns on an LED
only if the potentiometer goes above a certain threshold level. It prints the
analog value regardless of the level.

The circuit:
- potentiometer
Center pin of the potentiometer goes to analog pin 0.
Side pins of the potentiometer go to +5V and ground.
- LED connected from digital pin 13 to ground

- Note: On most Arduino boards, there is already an LED on the board connected
to pin 13, so you don't need any extra components for this example.

created 17 Jan 2009
modified 9 Apr 2012
by Tom Igoe

This example code is in the public domain.

http://www.arduino.cc/en/Tutorial/IfStatement
*/

// These constants won't change:
const int analogPin = A0;// pin that the sensor is attached to
const int ledPin =13;// pin that the LED is attached to
const int threshold =400;// an arbitrary threshold level that's in the range of the analog input

voidsetup(){// initialize the LED pin as an output:pinMode(ledPin,OUTPUT);// initialize serial communications:Serial.begin(9600);}

voidloop(){// read the value of the potentiometer:int analogValue =analogRead(analogPin);

// if the analog value is high enough, turn on the LED:if(analogValue > threshold){digitalWrite(ledPin,HIGH);}else{digitalWrite(ledPin,LOW);}

// print the analog value:Serial.println(analogValue);delay(1);// delay in between reads for stability}